lkml.org 
[lkml]   [2022]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5 03/11] tpm: Allow PCR 23 to be restricted to kernel-only use
On Mon, Nov 14, 2022 at 12:11:20PM -0500, James Bottomley wrote:
> On Fri, 2022-11-11 at 15:16 -0800, Evan Green wrote:
> > Introduce a new Kconfig, TCG_TPM_RESTRICT_PCR, which if enabled
> > restricts usermode's ability to extend or reset PCR 23.
>
> Could I re ask the question here that I asked of Matthew's patch set:
>
> https://lore.kernel.org/all/b0c4980c8fad14115daa3040979c52f07f7fbe2c.camel@linux.ibm.com/
>
> Which was could we use an NVRAM index in the TPM instead of a PCR? The
> reason for asking was that PCRs are rather precious and might get more
> so now that Lennart has some grand scheme for using more of them in his
> unified boot project. Matthew promised to play with the idea but never
> got back to the patch set to say whether he investigated this or not.

Even for PCR case it would be better to have it configurable through
kernel command-line, including a disabled state, which would the
default.

This would be backwards compatible, and if designed properly, could
more easily extended for NV index later on.

BR, Jarkko

\
 
 \ /
  Last update: 2022-11-27 17:35    [W:0.121 / U:1.232 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site